5.1-bugteam->5.5-bugteam merge

mysql-test/r/func_math.result

@@ -501,6 +501,19 @@ SHOW WARNINGS;
 Level	Code	Message
 Warning	1292	Truncated incorrect DECIMAL value: ''
 Error	1690	BIGINT value is out of range in '('123456789012345678901234567890.123456789012345678901234567890' DIV 1)'
+#
+# Bug#57810 case/when/then : Assertion failed: length || !scale
+#
+SELECT CASE(('')) WHEN (CONVERT(1, CHAR(1))) THEN (('' / 1)) END;
+CASE(('')) WHEN (CONVERT(1, CHAR(1))) THEN (('' / 1)) END
+NULL
+CREATE TABLE t1 SELECT CAST((CASE(('')) WHEN (CONVERT(1, CHAR(1))) THEN (('' / 1)) END) AS CHAR) as C;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `C` varchar(23) DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t1;
 End of 5.1 tests
 #
 # Bug #8433: Overflow must be an error

mysql-test/t/func_math.test

@@ -336,6 +336,15 @@ select 123456789012345678901234567890.123456789012345678901234567890 div 1 as x;
 select "123456789012345678901234567890.123456789012345678901234567890" div 1 as x; 
 SHOW WARNINGS;
 
+--echo #
+--echo # Bug#57810 case/when/then : Assertion failed: length || !scale
+--echo #
+
+SELECT CASE(('')) WHEN (CONVERT(1, CHAR(1))) THEN (('' / 1)) END;
+CREATE TABLE t1 SELECT CAST((CASE(('')) WHEN (CONVERT(1, CHAR(1))) THEN (('' / 1)) END) AS CHAR) as C;
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
 --echo End of 5.1 tests
 
 --echo #

sql/item_func.cc

@@ -1543,9 +1543,14 @@ void Item_func_div::fix_length_and_dec()
   {
     decimals=max(args[0]->decimals,args[1]->decimals)+prec_increment;
     set_if_smaller(decimals, NOT_FIXED_DEC);
-    max_length=args[0]->max_length - args[0]->decimals + decimals;
     uint tmp=float_length(decimals);
+    if (decimals == NOT_FIXED_DEC)
+      max_length= tmp;
+    else
+    {
+      max_length=args[0]->max_length - args[0]->decimals + decimals;
       set_if_smaller(max_length,tmp);
+    }
     break;
   }
   case INT_RESULT: